Compression Help

[phantom09086]

So I was veryupset on SAT when I tried to start my 95 GT that I just rebuilt. I have KeithBlack pistons, Trick flow heads and trick flow stage 1 cam, the KB pistons aremade for the TF Heads. When I cranked the car it just backfired. I pulled thetiming cove to check the timing, thought it could have been 180 off, went toput set the #1 on TDC on the compression stroke and nothing. Put a compressiontester on it and 0 psi. Took the timing chain off and released all the tensionon the valve springs so the valves would close. I then had my buddy hand crank the engine, still no compression in the spark plug hole but was getting sucking and blowing from the intake manifold. Now could this mean my valves need to be reseated or am I overlooking something. Any help would be great.

Thanks
Greg.

 

[wayne94mustang]

Sounds to me like you didn't check your piston to valve clearence and you bent some valves......

 

[Mustang Mark]

+1 on bent valves.

 

[phantom09086]

damn, that sucks. Guess ill be pulling heasds this weekend.

 

[Mrstangerbanger]

Its highly unlikely that you bent a valve with trickflow 170 2.02 heads and a stage 1 cam from not having enough piston to valve clearance.

I have the same heads and bigger cam with no problems and enough room to run a stage 2 cam easy.




have you been driving the car and everything was fine?

Please explain more thanks

 

[Venomized]

Is it just on that cylinder or multiple cyls? Also you may want to look into the piston itself. Did it backfire or detonate?

 

[phantom09086]

It back fired, but there is no compression in the 1 and 2 cylinders, I ran out of time to check the rest.

 

[Addermk2]

I gonna go with the rockers... I'm putting money on you not installing them correctly, or using the wrong pushrods.

Remove them all and gently tap on the valve tips with a small hammer. Each one should move smoothly. If any feel like they are bound up or giving an odd "thud" when you tap them, then you have problems in the heads (bent valves). Another thing you can do is rotate any cylinder to BDC and put your finger over the spark plug hole while you turn the engine back to TDC. Is air still going out through the intake?

Pull your pushrods out and roll them across a flat surface. Are they bent?

Before you go blindly ripping things apart, check, check, and recheck that you did everything right.

 

[BlkoutGT]

I gonna go with the rockers... I'm putting money on you not installing them correctly, or using the wrong pushrods.

Remove them all and gently tap on the valve tips with a small hammer. Each one should move smoothly. If any feel like they are bound up or giving an odd "thud" when you tap them, then you have problems in the heads (bent valves). Another thing you can do is rotate any cylinder to BDC and put your finger over the spark plug hole while you turn the engine back to TDC. Is air still going out through the intake?

Pull your pushrods out and roll them across a flat surface. Are they bent?

Before you go blindly ripping things apart, check, check, and recheck that you did everything right.

+1 How are you installing the rockers?

 

[phantom09086]

Push rods are PRW Chromoly Push Rods 6.700" Length 5/16" Diameter, rockers where installed by taking out the play in the push rod and then the hex bolt in the center was torqued to spec. Now the first set of pistons I installed where wrong, The clearance was off, and they did make contact with the valves, but only while hand turning the engine. Not sure if I can bend them while hand turning. It did leave marks on the pistons.

 

[BLOWN 95GT]

You mean you installed two different sets of pistons? Im lost but anyway. If you turned the motor over by hand with a pull handle hard enough to leave marks on the piston you probably bent a valve how much pressure did you put on the bar SHREK. Did you stop pulling or pushing as soon as it stopped or did you keep trying to pull or push on it.

 

[BLOWN 95GT]

So I was veryupset on SAT when I tried to start my 95 GT that I just rebuilt. I have KeithBlack pistons, Trick flow heads and trick flow stage 1 cam, the KB pistons aremade for the TF Heads. When I cranked the car it just backfired. I pulled thetiming cove to check the timing, thought it could have been 180 off, went toput set the #1 on TDC on the compression stroke and nothing. Put a compressiontester on it and 0 psi. Took the timing chain off and released all the tensionon the valve springs so the valves would close. I then had my buddy hand crank the engine, still no compression in the spark plug hole but was getting sucking and blowing from the intake manifold. Now could this mean my valves need to be reseated or am I overlooking something. Any help would be great.

Thanks
Greg.

You should not have to pull the timing cover to see if the timing is 180 out. It is very easy to set a timing chain, bring #1 piston up to tdc make sure and install the chain with the two marks lined up. Did you check the distributor to make sure it wasn't 180 out? Just asking because you never mentioned it, and that would have been the first thing I would do. Lots of first time builders also make this mistake. Turn the motor over by hand to bring number 1 piston up to TDC, make sure the timing marker is pointing at the 0 on the harmonic balancer, install the distributor so the rotor button is pointing at the plug wire on the distributor cap going to the number 1 cylinder and make sure you have the rest of the plug wires installed on the cap in the correct firing order. But if you pulled the rockers and pushrods on the cylinders you tested and still have no compression you probably did bend some valves.

 

[Venomized]

Only reason i asked about detonation is because there seems to be a lot of threads lately about KB pistons having issues with quality.

 

[phantom09086]

Ok, Sat I did a compression test and found the #1 intake valve was bent. Pulled the head and checked the rest of the valves and that was the only one, I also checked the push rods and all where straight. I did have the wrong spark plugs. I am still confussed, maybe im wrong but I dont thing 1 bent valve and wrong would cause my car not to start. Any other ideas ?

 

[BLOWN 95GT]

Your distributor could be 180 out! But I would get that valve fixed and worry about the clearance issue first. Then see if you can restab the distributor again.

 

[phantom09086]

Valve is on the way, and the clearance is good now since the pistons where changed out.

 

[wayne94mustang]

Valve is on the way, and the clearance is good now since the pistons where changed out.

But did you check the clearence?

It don't sound like you did.......

 

[phantom09086]

yes i checked the clearence when I installed the the new pistons that are made for trickflow 170 heads, but I already had a bent valve from the pistons I first installed. Didnt know I had to use special pistons for TF

 

[phantom09086]

Ok, just to make sure Im doing my rockers correct, I get the cylinder to TDC then tighten the nut till the valve lash is out, then torque the center allen screw to spec. is this correct??

 

[phantom09086]

Valve installed, rockers set and it came to life, thanks everyone.